Study of Acids Bases and Salts


   
 
Indicators
Indicators are the chemicals that when added to solutions show whether the solution is acidic or basic, by a sudden change of their colour. The common indicators used and the colour changes observed are mentioned below:
 
 
The indicators ordinarily used in the laboratory only indicate whether the solution is acidic, basic or neutral. They cannot give any idea as to the comparative strength of various solutions.
 
However a 'Universal indicator' is used, which is a mixed indicator. It not only shows whether the solution is acidic or basic, but also shows the approximate pH values by giving a wider range of colours for different values of pH (Fig. 8.5).
 
 
 
     
   
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